A UAV is a remotely piloted or self-piloted aircraft that can carry cameras, sensors, communications equipment, or other payloads, is capable of controlled, sustained, level flight, and is usually powered by an engine. A self-piloted UAV may fly autonomously based on pre-programmed flight plans.
UAVs are becoming increasingly used for various missions where manned flight vehicles are not appropriate or not feasible. These missions may include military situations, such as surveillance, reconnaissance, target acquisition, data acquisition, communications relay, decoy, harassment, or supply flights. UAVs are also used for a growing number of civilian missions where a human observer would be at risk, such as firefighting, natural disaster reconnaissance, police observation of civil disturbances or crime scenes, and scientific research. An example of the latter would be observation of weather formations or of a volcano.
As miniaturization technology has improved, it is now possible to manufacture very small UAVs (sometimes referred to as micro-aerial vehicles, or MAVs). For examples of UAV and MAV design and operation, see U.S. patent application Ser. Nos. 11/752,497, 11/753,017, and 12/187,172, all of which are hereby incorporated by reference in their entirety herein.
A UAV can be designed to use a ducted fan for propulsion, and may fly like a helicopter, using a propeller that draws in air through a duct to provide lift. The UAV propeller is preferably enclosed in the duct and is generally driven by a gasoline engine. The UAV may be controlled using micro-electrical mechanical systems (MEMS) electronic sensor technology.
Traditional aircraft may utilize a dihedral wing design, in which the wings exhibit an upward angle from lengthwise axis of the aircraft when the wings are viewed from the front or rear of this axis. A ducted fan UAV may lack a dihedral wing design and, therefore, it may be challenging to determine which direction a ducted fan UAV is flying. Consequently, it can be difficult for both manned and unmanned vehicles to avoid collisions with such a UAV. As UAVs are more widely deployed, the airspace will become more crowded. Thus, there is an increasing need to improve UAV collision avoidance systems.